824
FXUS66 KSEW 162142
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
242 PM PDT Sun Jun 16 2024

.SYNOPSIS...An upper level trough over Western Washington will
shift east of the area on Monday. High pressure aloft will
gradually build through the week for a trend toward drier and
warmer conditions. Another upper trough is expected to approach
the region late next weekend for a cooling trend and a returning
chance of showers to portions of the area.

&&

.SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Scattered showers
continue across the area this afternoon as an upper trough over
the area gradually shifts southeastward. The trough axis will be east
of the Cascades on Monday, but continued weak troughing aloft
will keep clouds and a chance of showers in the forecast. Heights
continue to rise on Tuesday with onshore flow weakening. This
will allow much of the area to clear out by Tuesday afternoon
with temperatures bouncing back to near seasonal levels. Upper
ridging centered well offshore continues to strengthen on
Wednesday as 500 millibar heights approach 570 dam with 850
millibar temps approaching 14 C. With thermal troughing just to
our south and only weak onshore flow, much of the interior of
Western Washington should warm into the mid to upper 70s with 60s
along the coast.

.LONG TERM /THURSDAY THROUGH SUNDAY/...Low amplitude ridging
continues to build across the area Thursday and Friday for
continued dry and warmer conditions with portions of the interior
from Seattle southward reaching near or above 80 degrees.
Ensembles are in fairly good agreement that the ridge axis will
shift east of the region early in the coming weekend as an upper
trough deepens along the British Columbia coast. This will result
in a cooling trend along with a returning chance for
showers...especially over the Olympic Peninsula and across the
North Interior. 27

&&

.AVIATION...Broad upper low over the Pac NW tonight with a cool
and slightly unstable air mass over western Washington. Showers
will mostly affect the mountains and South Sound this evening,
with light rain persisting in the interior early Monday morning.
The flow aloft is northerly. Drier conditions expected Monday
afternoon as the upper trough departs east. 33

KSEA...Showers in the vicinity this afternoon and early evening.
W/NW wind to 10 kt through 06z, becoming S. Low clouds, light rain
and MVFR conditions early Monday. 33

&&

.MARINE...High pressure over the NE Pacific will maintain onshore
flow over western WA this week. Highest wind and waves will be
through the Strait of Juan de Fuca, mainly during the afternoon
and evening hours. 33

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Monday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

&&

$$